Step Up Is The Only Feeding Bottle That Allows You To Feed Your Baby Naturally Throughout Every Growth Phase As It Is The Only Bottle That Is Able To Adapt To The Changes In The Sucking Action Of The Baby Over Raised Rings: To Help The Baby Find And Maintain The Correct Position Of His Tongue And Simulates The Wrinkles Of A Mother?S Nipple. Step Up 3 6M+ 330 Ml: Food Flow Longer Teat To Encourage Correct Swallowing. ?Rings On The Base Of The Teat For Extra Suppleness During The ?Sucking? Motion. ?Raised Rings On The Teat To Help Babies Position Their Tongue Correctly Less Rounded Base: To Guarantee Tighter Lip Support Which Helps The ?Sucking? Motion